My primary research objective is to decipher transcriptional control in development based upon an evolutionary theoretic approach. A long-standing problem in developmental biology is to determine the genetic basis for the remarkably robust network of events that specify the development of a multicellular organism. The nematode C. elegans makes for a convenient model in this effort, exhibiting both cell-autonomous and cell-cell communication modes of development. While the highly uniform cell lineage of this organism has been elegantly studied, revealing a number of master regulators, little is known about the constraints that act upon the participating genes throughout development. We hypothesize that a comparison among wild C. elegans isolates and with extant Caenorhabditis species would reveal the evolutionary plasticity of the process in molecular detail. Our approach involves comparing, on a gene by gene basis, the effect of two evolutionary time frames: micro-evolution through a comparison of wild isolates and macro-evolution through a comparison with divergent Caenorhabditis species. Provided that sufficient variation is detected among the nematodes, the comparative transcriptomic data promises to resolve the available time course data by identifying the mode of evolution (purifying, positive, and neutral) for each time point of each gene. These predicted modes are experimentally tested by the use of reverse genetics and transgenic strains for a set of genes with interesting conservation and divergences in gene expression. [unreadable] [unreadable] [unreadable]